unsuccessful

Unsuccessful is an adjective used to describe an outcome that did not achieve its intended objective. It can apply to people, projects, events, experiments, or plans, and its use is typically factual rather than moral, although tone and context can influence interpretation. The term sits opposite successful and is often chosen when the result falls short of expectations without necessarily implying deliberate failure.

In nuance, unsuccessful may indicate a complete failure or merely a partial or temporary lack of success. It can reflect external factors, insufficient resources, poor planning, or execution issues, rather than personal fault. In evaluative writing, it is common to pair it with explanations of what went wrong and what was learned, as in an unsuccessful launch followed by a revised strategy.

Common collocations include an unsuccessful attempt, an unsuccessful campaign, or an unsuccessful outcome. In research or business reporting, describing results as unsuccessful is a way to convey that predefined success criteria were not met, while still allowing for future iteration or improvement.

Etymology: the word is formed by adding the prefix un- to the adjective successful; successful itself derives from success, from Latin successus via Old French. Related terms include failure, ineffective, unproductive, and, antonymously, successful.